Control for internal-combustion engines



4 Sheets-Sheet l F. C. MOCK ETAL CONTROL FOR INTERNAL-COMBUSTION ENGINES Filed Sept. 26, 1947 March 27, 1951 March 27, 1951 F. c. MocK x-:T`AL

CONTROL FOR INTERNAL-COMBUSTION ENGINES 4 Sheets-Sheet 2 Filed Sept. 26, 1947 .MN NN R uw March 27, 1951 F. c. MocK ET A1. 2,546,902

CONTROL FOR INTERNAL-COMBUSTION ENGINES Filed Sept. 26, 1947 I 4 Sheets-Sheet 3 IN VEN TORS F/P/I/VA/a fac/s BY ww/v 6. ifa ff? MQW/ March 27,v F, C, MQCK ET AL 2,546,902

CONTROL FOR INTERNAL-COMBUSTION ENGINES Filed Sept. 26, 1947 4 Sheets-Sheet 4 OIL FLOW ).55 PER MINI/TE soo woo :zoo uw Iwo moo zoo 2m 240e ma ma m am SUPERCHARGER RPM.

ALTITUDE ZF 1E- E ,www

Patented Mar. 27, 1951 CONTROL FOB NTERNAL-COMBUSTIGN ENGINES Frank C. Mock, South Bend, and Edwin G. Keller,

Michigan City, Ind., assignors to Bendix Aviation Corporation, South Bend, Ind., a corporation oi' Delaware Application September 26, 1947, Serial No. 776,296

(Cl. 12S-103) 17 claims. 1

This invention relates to a power control system for supercharged aircraft engines whereby a given power output may be automatically maintained at varying altitudes as determined by the setting of a power control lever or quadrant; it is particularly adapted for use with a supercharging system employing one or more fluid or hydraulic couplings for varying the engine-to-supercharger speed ratio.

Anobject of the invention is to provide an irnproved boost or power control system for supercharged aircraft engines by means of which a given manifold pressure, as selected by a pilot, will be automatically maintained from yground level up to high blower critical with a minimum of hunting or instability.

Another object is to provide power control mechanism for aircraft engine supercharging systems utilizing one or more engine driven iluid couplings wherein hydraulic lluid is metered to the couplings as a function of manifold pressure datum, altitude and engine speed.

. Another object is to provide a coordinated throttle control and hydraulic coupling control in a system of the type specified which will respond promptly to a pilots demands with a minimum of hunting or surging.

Another object is to provide in a hydraulic coupling supercharger control system means whereby a moderate variation in the oil supply pressure will not appreciably aifect the operation of the control.

Another object is to coordinate in a power control device, a throttle control and a hydraulic coupling control without involving complicated interconnecting and antihunt mechanism and as a result of which the device may be made relatively simple and light in weight.

A further object is to improve the operating characteristics of the oil metering valve which is usually present in power control systems of the uid coupling type.

A still further object is to provide a new method of regulating the speed of a supercharger driven from an engine through one or more hydraulic couplings, based on the discovery that the speed of the supercharger connected to the driven side or element of a coupling is a substantially direct function of oil or other hydraulic fluid flow to the coupling at practically any speed of the engine which drives the other side or element of the coupling.

The foregoing and other objects and advantages will become apparent in view of the following description taken in conjunction with the drawings; wherein:

Figure 1 is a view in elevation of an aircraft engine and coacting supercharger system having the power control of the present invention operatively associated therewith;

Figure 2 is a schematic sectional elevation of the power control mechanism with the engine and supercharger drive system omitted;

Figure 3 is an enlargement of the oil coupling valve and coacting mechanism as shown in the central portion of Figure 2, to more clearly show the various parts and provide room for reference numerals;

Figure 4 is a detail longitudinal sectional view of the oil coupling valve, showing an alternate position of the parts of the valve with respect to the showing in Figures 2 and 3;

Figure 5 is a curve chart, plotting oil flow against supercharger speed, to illustrate how the R. P. M. of the supercharger is a direct function of oil flow to the fluid coupling at any engine speed; and

Figure 6 is another curve chart, illustrating theoperation of the control.

Referring to the drawings, and first to Figure l, an aircraft engine Il) has an air induction conduit I I, Ii which receives air from an air scoop or like device, part of which is indicated at l2. For the purposes of illustration, the air induction or input system is of the multi-stage type, including a supercharger I3, herein termed the main stage, which is engine driven with a xed gear ratio and supplies pressure under all conditions of operation, and a superchargel` I4, herein termed the auxiliary stage since it is regulated to supplement the supercharger i3 under certain conditions of operation, as at wide or nearly wide open throttle, when the capacity or critical of the main stage supercharger is reached. A charge forming device such as a carburetor is shown at I5 including a venturi I5', and posterior the venturi is a throttle valve I6 for variably limiting the supply of air iiowing to the intake manifold Il of the engine and thence to the respective engine cylinders. A stop I6 limits the wide-open 'position of the throttle. The engine is equipped with a propeller I8, preferably but not necessarily of the variable pitch type, the pitch of the blades being adjustable through the medium of a gover nor I9 regulable by a lever 2l! which in turn may be under manual or automatic cont-rol, as desired. Since propeller pitch governors have long been known and used for controlling the speed of aircraft engines and may be purchased as a com- 'plete unit in the open market, the governor is returned te the tank 2l through return'line'Zi and cooler 25. The engine may be vented to the top o1' the oil tank through line 25.

rihe drive on the auxiliary stage supercharger irl is transmitted from the `engine or ether suitable power source through variable speed hydra-ulic coupling units generally indicated ati?? and 271, which may .be of similar construction and ihave-siinilar operating characteristics, -Iydrau- 'lic couplings of this type are well knownin'the art 4and may befpurchased in the open market. In general, each unit consists of va drivingrotor 'or impeller 23 anda driven rotor crvvaned runner Z9 mounted in a casing 30, oil under-pressure being conducted to the unit through conduit 3l. The rotor 28 is usually driven from a suitable power source through step-up or step-:down transmission; in the present instance itis shown secured on ashaft132 driven from thefengine through gearing S3, rhe drive transmitted-to the unit 2? is cfa ratio higher thanthat of the unit 2l so that the two units will cover arange of speed sufiicient to give the necessary auxiliary charging capacity for rated altitude without necessitating excessive slippage at'higher'supercharger output powers. YrI-he rotor Yor vaned runner 29 drives a shaft St'carrying a gears35. Corresponding parts of the coupling unit 2l" have lbeen given corresponding reference numerals except that prime has been added. "The gears 35, 35 and lie, 36' form part of aA transmissionV system for driving AVtlfiesupercharger lli.

Oil `under pressure fed to therotorsthrough 'conduits 3 l, 5 reduces the slip between the drivingrotors 2B, 28 and the driven rotors Vor runners 2i?, 29', the amount of slip'being'in relation tothe rate of feed of the oil. With little or no oil feed, the rotors orrunners `29, vL29 simply idle/or producevery little additional load on the system. Oil fed to the 'coupling is eventually thrown outwardly through bleeds formed'in the'rotors and i5 returned'to the drain system through conduit 3l. "The conduit 3| to'the'low speed couplingis controlled by a valve v38 loperatingto vclose the said conduit when'tlie .driven shaft 35i rotates faster than the driving shaft 32. This action causes the low speed coupling Vto automatically emptywhen the high v,speedicoupling'attains a predetermined speed and overdrives the low speed couplingftothereby avoid loss of power which would otherwise be absorbed by the rotating oil-nlled'low speed coupling, The valve 38 -is shown schematically, Vsince it` forms no part of the present invention.

The-various-parts which go to make up'the power control device are mounted in a main casing or housing it and are shown schematically in Figures 2 and l3 to avc-id a multiplicity'of sectional views. Basically, the device provides for control of manifold pressure by automatic and/ or manual regulation of the carburetor throttle vup to some predetermined altitude or condition of air Vdensity, usually termed the "first critical and requiring a wide-open throttle, and beyond this point, the manifold pressure is .controlled by automatic regulation of the flow of iiuid to the hydraulic couplings; the carburetor throttle control and hydraulic coupling controls being correlatedfunctionally although'theyiare` to a large extent'independently operative, tending to irnprove stability and response characteristics.

Control through regulation Of the carburetor throttle This part of the control was originally disclosed rand claimed in the copending application of Frank C. Mock, .Serial No. 440,669, led April 27, 1942, nowV Patent No. 2,453,651, and in a modiiied form in the-copending application of James M. ljastmanfetal., Serial No. 685,942, filed July 29, 1946; it is claimed in the instant application only insofar as the combination thereof with the hydraulic control produces a new and/or improved result.

A^main shaft vil (see Figure 2) is'journaled in the housing lll and has secured thereon exteriorly of the housing the one extremity'of a lever @2, said lever being provided withfan extensions? projecting upwardly beyond the shaft ill and carrying a stub shaft v1152 rotatably mountinga pinion gear-4S. The lower or opposite end 'of lever l2 is pivotally connected to the carburetor throttle by linkagelii, dll', A main power .control .lever is indicated Aat li5 in'Figure 1; it connects through link 45 witha'lever d5 (Figu1'e.-2);piv otally mounted on the shaft-si, also externally of the casing dil, and at its'upper extremity'be- Vyond said shaft the lever terminates :in 1.a

cam shaped portion provided withifa laterallyoiflset toothed segment or sector gear i6 in mesh with the pinion d3 carried by the extension-42' .of the throttle lever t2; and saidpinion in turnis in mesh vwith one set of .teeth 8' ofa segmental gear d8, loosely. or pivotally mountedon the main shaft lli and provided Awith another set of teeth 48 in mesh with a toothed rack :i9 .secured on a piston..rod 5E, shown asYof'I-.beam shape .in cross section and terminating at. its opposite ends ink pistons 5|, 5l ,slidable in cylinders 52 and '53. ln the cylinder 52 is a spring 5d which at-,one end abuts the piston .5i .and normally .urges Jit `and consequently the rack 49 toward the extreme left hand position (closed throttle position), andat its opposite end engages in a recess formed in the rear end'wall of the cylinder52.

The rack i9 is actuated by fluid under pressure admitted to the cylinders52 and 5S cya-servo valve 55, whose'position is determined by a variable datum manifold pressure assembly including an evacuated bellows or aneroi'd mounted in a sealed chamber 5l' denned in part'by a cupshaped wall 58 and in part by Aa'diap-hragrn`59 whose central portion is clampe'dbetween a pair of reinforcing plates connected to va cup-shaped guide member 59 having'an encircling bushing at one end mounted for limited sliding Amovement in a cylinder Si and at its oppositeend provided with a ball head slidingly lmounted in a guide bore cr passage 62 which is provided with'a vent 52 to facilitate evacuation of the bellows, after which the vent may be closed by a screw'or other suitable means and the vent sealed. The bellows may be evacuated to a low absolute value and rendered responsive to changes in pressure only, or it may be evacuated and loaded with atemperature responsive inert gas and a damping 'fluid to render the bellows responsive to changes 'ent to Mock et al. No. 2,376,711 for a suitable density responsive capsule of the latter type.

The desired manifold p-ressure datum is determined by variably loading a datum spring 63, which at one end abuts a datum piston 64 slidingly mounted in a cylinder E5 and at its opposite end abuts a thrust plate 66 forming part of a thrust bearing carried by an abutment or contact plate 6l secured on the one extremity oi a datum rod or shaft E8, the opposite end of said v rod or shaft having connected thereto a ball headed bolt 68 which engages in a socket at the adjacent end of the guide 65 and provides a universal joint connection between the datum rod 68 and the movable end of the bellows 55. A sealing diaphragm 69 seals the space around the aneroid shaft 63. A datum cam l@ is formed on the upper cam shaped extremity of the lever 45 so as to be rotatable through adjustment of the lever 45, the cam J5 being engaged by a follower mounted on a lever 'I2k which is pivotally suspended at 'i3 from a stationary depending bracket 13. A compression spring 54 normally urges the follower lever l2 in a clockwise direction, tending to maintain the follower 1| against the cam l0. A link 85 is pivotally connected at one end to the level1 'l2 and at its opposite end is pivoted on a pin 8| which is carried by a swinging arm 82 and also serves as a floating pivot or fulcrum for a servo lever 33 whose upper end is operatively connected to a servo valve 84, designed to control admission of iluid under pressure to the cylinder 65 in back of the piston 64 in a manner to be described. The lower end of lever 33 is contoured to engage the datum piston 64, being held against it by the action of servo valve spring 84'; and the relative dimensions of said lever and the parts which make up the oating pivot 3i therefor are such that the travel of pivot 8| acts to move servo valve 84 in a direction to cause oil pressure change in back of piston 64 to move said piston and lever 83 and return servo valve 34 to the position shown, thereby setting the load on spring S3 in accordance with the travel of pivot 8! to determine the datum setting. Utilizing a servo motor to tension the datum spring relieves the pilot of considerable manual effort to eect this operation.

A servo lever 35 is pivoted or fulcrumed at 85 to a stationary bracket, and at its upper end said lever is engaged by contact plate 61 and at its lower end engages and actuates servo valve 55 to the left against the tension of springs 31, 87| mounted in a cylinder 88 and having a damping piston 82 interposed therebetween.

The various operating pressures in the now ducts, servo valve ports, servo piston cylinders and the like, have been designated as follows:

. P IS-feedback damping piston presure P|4aneroid chamber pressure P--I E-datum piston pressure Operation of the throttle control In the position of the parts as shown in'the drawings, the pilots control lever 45 (Figure l) has been advanced to a relatively high power setting, thus calling' for a manifold pressure of, for example, between 64 to 84 inches absolute. At this time, cam follower (Figure 2) is in engagement with the high portion of datum cam the floating pivot 8| is in its right hand position andthe datum spring 63 is loaded suiciently to hold the bellows 55 in a balanced condition at the existing manifold pressure and air density. Also, the servo valve 55 has been located to admit oil under pressure (P-4 pressure) to the left hand side of the throttle piston 5|', which pressure has moved the pistons 5|', 5| and rack gear 4S to the right and at the same time has permitted oil to drain (P-3 pressure) from the right hand side of piston 5|; movement of the rack gear 49 to the right having rotated segmental gear 48 counterclockwise, and since sector gear i5 is held against rotation by lever this action has caused the pinion t3 to roll counterclockwise and act through lever 42 and link rod 46 to rotate the throttle I6 (Figure l) lto its Iwide open position.

The cam 'i0 may be and preferably is contoured to obtain direct manual. throttle control over a predetermined low range of manifold pressures; above this range the throttle being automatically positioned once the datum is set by the power lever 45. Thus, at sea level with the throttle nearly closed and the engine idling, pistons 5|, 5| would be to the extreme left position and the cam follower 7| would be on the substantially true radius or ineffective portion 'lli' of cam le; and as long as the follower 1| remains on this low cam portion, movement of the power lever t5 will rotate the gear 46, but will not actuate the servo valve 84 suiciently to move the pistons to the right against the force of spring 54. This will hold the segmental gear 48 against rotation, so that manual actuation of the gear 45 through levers 45, 45" will roll the pinion 43 on gear teeth 48 and in turn actuate lever i2 to open and close the throttle.

Should the lever 45 be advanced from a low power position to an increasingly high power position such that the cam '50 (acting through lever or arm l2, link 3Q, floating pivot 3|, servo valve 84 and datum piston 64) increases the load on the datum spring |53 to a point where the spring force overcomes the pressure tending to hold the bellows 55 collapsed, the datum rod 5B will move to the right and in turn move servo valve 55 to the left and high pressure fluid P-2 pressure) will pass to chamber 53 on the left hand side of piston 5| and oil will drain from chamber 52 on the right hand side of piston 5|. Throttle pistons 5|, 5| will then move to the right and, acting through rack 49 and gear 4S, will roll pinion 43 counter'- clockwise on gear 46 and open the throttle le. The control then becomes automatic, or the boost control takes over, the pilot selecting thedegree of manifold pressure or power output by positioning the cam 10, which is turn locates the floating piv- Should there be a decrease in air density, as by a gain in altitude, manifold pressure P-I at the right hand side of diaphragm 59 and the pressure P-'M in chamber 5l will likewise decrease, and the aneroid or bellows 55 will tend to expand vor extend itself, thereby moving the datum shaft G8 to the right, turning servo valve lever 85 clockwise and `moving the servo valve 55 to the left; whereupon high pressure oil ows from P-Z 'Tage/6,902

7 ichannelto' P-dichannel anddrain 'oil isalsofbled .'fromP-e' channelr to P-S channelvand pistons i|',.5|1move"to' the right, turningsegmental gear v"'l5Seeounterclockwiisezand rolling. pinion' 23; to the lft; thereby-movingthrottle lever i2 to theright crin a direction to open the 'throttleand increase `the manifoldpressure'until the pressure YVon'the right offdiaphragm' 5! andfinV chamber 5? balances the'datum setting of theV spring" 53.

f Shouldthere beV` an increase in air density,

v'b5/'a' 'drop in altituda'pressure `P-l at thel right 1 of diaphragm and pressure P-l in chamber 5T will li'kewisezincrease, bellows 55 will tend to icollapse, thereby permitting datum spring B31to I and reduce manifoldpressureuntil P-| on the' right side of' diaphragm 59 balances the datum :setting of: spring 63.

Auxiliary stage sufoerchlarger 'hydraulic coupling contre A coupling valve is generally indicated at |99 (compare FiguresZ. and 3). In the form shown, it comprisesa cylinder iii! formed with a series of lowcoupling metering holes or-orirlces |92- and .high coupling metering holes or orifices |93. The i action of these metering oiices is general-ly similar to that oi a metering valve; they may consist of a series of holes formedvthrough the wall o vfthe cylinder IB! and arrangedV in spiral or screw forma'tion and ofigradually increasing flow cas-oacity, or in'a manner such that there is an increase in iiuid delivery in substantiallyfdirect relation to'linear movement of valve member i t4.

For reasons which will subsequently ex- 'Jplained,` it is of advantage to have annick opening. movement of 'the valve HM, or to produce' a snap` action when the valve Iefa Ainitially moves to a meteringposition. lTo produce this.. snap action, the valve member led is mounted iorlimited /sliding movement on a stepped cyiindrical mem# ber i'ioi'nied with a shoulder or stop |66 and `.an annulus lill,Y an oil pressure chamber i533 beingv defined betweenfsaid Vannulus and the adi, jacent endof the valve iisd. :'.lfhe'memb f lili-.is :in turn slidably-mounted on the stem Ipor ion |539 Y oa-plunger i le; the latter1- having a piston. i i i '-atfone end thereofa'nda-n'annulus or -d-isc |2f'at ,its opposite end. *A chamber |23 is dencd-beitween the piston i i and adjacent end of the yan- "rnulus ml, vand'afstoprshoulder` Hd limits'emove ement-t of 'the' member |35 toward: thepiston i 'when thevalve is closed. Avspringl H5' normally urges Vtl'iefplunger and valve. assembly towardreturn or closed position; and additional springs H6 and iV? 'normali-J urge the valve' Fll toward i thestop i ce and tha-member toward the stop 5d. Vents" i ix'an'd" |'i icommunic'atechambers l'ieiarui 13 withfdrain or'fP-:LS pressure. `Ports 1 Re' and l2 |1' admit oil under PQZlpressureto chambers i138 and H3, respectively, when uncovered by inward travelof the valve'assembly.

The valve' assembly operates as'v follows:

linthsfposition of theparts .in liguresfZaarid. 3,'

inwardly against :disc i member |54 therewith, which actionY will initial- -ly- 'start metering across theforiiicesl 03 at-apre- `the Svalvenfmember :5161i has been moved fito. full metering position with respect -to orifices y |02 (low. or intermediate blower coupling) and to an intermediate metering position with respect to orifices H33v (high blower coupling). At thistime,` oilwunder pressure has been admittedtoiiboth `chambers Ii'andI i I3 and -has moved the valve v member IM to' its innermost position away .from f'stop. i535, and has also moved the annulus 91T-to its innermost position away from stop ||4,com "pressing springs 5 and- The closed position of the' valve assembly is shown inrFigurel; `note -thatports |20 and |2|-are closedA and the valve --member |94 Vis upiagainst the stop |96 andi. the

vannuius iiil-isagainst stop ill. Ii the plunger f i il is now pushed-inwardly to a point where Valve member Ide uncovers 'port i 2o, oil-under pressure Jill :be-- admitted tol-chamber |98 `and move the saidrvalvemember'up againstlstop flange |22, kwhich vmovement i will initially start metering 'v across vorifices 'l 52 at la predetermined eieetive vrate rather than'at' a-slow initially ineffective rate;f=and"when the `annulus |97 uncoversiport i2! oil 'under pressure will be admitted to chamber H3 and the member |85 will suddenly move ||2,' carrying the valve determined effective rate. When the plunger. l l0 is-` retracted and oil `under pressure 4isclosedaoff yi'r-onrchambersA Hi8 and ii3,-.residualoilin-said chambers bleeds to drain through ybleeds H8. and

i|9-and the springs H6 land EH move-.theman- Vnulus il'fagainst stop H4 and valve member .IEM `'against stop me.

Hydraulic fluid,- here-oil -under engine or. P-2

fpressureyiiows through :entrance ports 2t-into valve chamber |25.

From this :chamber the oil is metered 4through metering oriiices iZand |03 toregulator valve chambers |26 and I2?i and rthe. fmetered oil. then -ilows by vway of valveport-s |7218 VYand |2S and chambers iZand- |29 to the P 8 :and P| 0 feed passagesor conduits -for--vthe=low 'f and .high couplings 2 'a'. and Z l The valves'designated at |33 and I3 l. coactIwith valve iiand. a -iiyweight speed-indicator 15|, .Figure-2, to Vmeter oil rto the couplings-as .a function of engine-speedy ina manner Aand `fora purpose to-bedescribed; theyare mountedto slide in cylinders |32 and |33 againstthe resistance of springs i34fand |35.

Regulation of the valve wlifis coordinated with manifoldpressure'selection by means of a cam t |35,-Figure2, shown as formed integral with the cani lil,- `more` Afor the lpurpose of f accommodating 4-the particular schematic *arrangementA of parts uthan-as la practical design, since it could: be` a separate@cam` .rotated vin .any suitablemanner as long as it is synchronized with the cam 10. The cam |36 engages v-afollower or roller 38 mounted on the adjacent end oa-rod 13d, which in turn is connected to a rod |39 throughfaninterposed aneroid or'densityresponsiveY bellows-|48 loaded with a spring-65 -set to maintain the' bellows "|48 in a predetermined condition of balance with respect to groundllevel'densityjor-` pressure and temperature. A' return spring |l|2"normallyurges the follower i391 againstthe surfacev of the-cam |35. The'bellows' orv aneroid Idil 'is mounted in a housing |43 whichdenes a 'chamber |44 adapted to have scoop or- 'carburetor entrance pressure communicated thereto by meansfofa conduit |45.

The outer free end of the rod |39" is formed lwith aguide slot 'i inlwhi'ch a' pin |41 has moverod |48 with a ball head |49 engaging in a bushing |59 forming part of the engine driven fly weight speed indicator assembly generally indicated at I| and comprising a pair of weights |52 pivoted on a yoke |53 formed on the end of a shaft |54 having secured thereon a drive pinion |55 adapted to be driven from the engine by suitable driving connection or gearing, not shown.

A link rod |51 is pivotally connected at one end to the cam |85 and at its opposite end to the one arm of a bell crank |58, the other arm of said bell crank being provided with a follower |59 engaging in a track or groove |59 formed in a lever |S, the latter having an intermediate portion formed with an angulated slot |62 in which the fly weight actuated pin |41 also engages. Beyond the slot |52, the lever |5| is pivotally connected at |53 to the valve plunger i0.

The speed responsive valve |64 provides a metering pressure differential across metering orifices |52 and |53 proportional to the rsquare of engine speed so that oil flow to the couplings will be proportional to engine speed; it is slidable in a chamber |55 and formed with ports |55, through which oil flows from an entrance channel |61 to chamber |55 and thence by way of channel |58 to port |24, and it is operatively connected to the engine driven governor |5| by means of a rod |55, lever |16, rod |1|, piston |12 and spring |13. The spring rate of spring |13 relative to that of springs |34 and |35 is preferably such as to substantially equal the constant represented by each spring |34 or |35 plus drain or P-3 pressure resistance against opening movement of said latter valves.

When the engine is running, the ily weights |52 move outwardly and inwardly in relation to engine speed and position the valve |ii4 as a function of engine speed. This will produce a differential across the metering orifices |52 and |63 proportional to the square of engine speed, and hence the ow through the oriiices will be proportional to engine speed directly.

We have discovered that the speed of a supercharger driven through a iiuid coupling varies as a function of the rate of iiow of oil to the coupling, as illustrated'in Figure 5. This may be explained as follows: If at a given oil flow the speed of the driven side of the coupling should be increased, the peripheral speed of the latter will correspondingly increase and there will be a proportional increase in the amount of oil thrown out to drain. This increase in the rate of escape of oil to drain at a constant rate of flow to the coupling compensates for the increased speed on the driven side oi the coupling, and although the ll is reduced and the slip increased, the speed of the driven side of the coupling remains substantially constant. Again, should the driven side of the coupling slow down at a given oil flow to the coupling, the peripheral speed of the driven side will correspondingly decrease, there will be less oil thrown out to drain, and thel increased ll and reduced slip will compensate forI the reduced driving speed.

' Reverting now to the oil metering device of Figures 2, 3, and 4, since oil is metered tov the couplings at a rate proportional to engine speed, the speed of the supercharger will also vary proportional to engine speed. Thus, a valve position of valve |04 giving a certain percent of coupling slip at one engine speed will give the same percent slip at any engine speed, and hence the valve position for minimum slip on the low coupling will always be the same. This permits locating the port |2| at a point such that when minimum low coupling slip is reached, further travel of the valve piston |09 will cause a snap action due to sudden pressure build-up in the chamber i I3, opening the high coupling metering oriiices 93 immediately so that there will be enough oil supplied to the high coupling to cause the latter to quickly overdrive the low coupling. Thus, oil in any appreciable quantity is never fed to both couplings at the same time for any continuous running condition and which would cause the couplings to buck each other, producing excessive heat rejection to the oil and wasted power.

Operation of coordinated throttle and fluid couplzng supercharger control When the pilot moves the power control lever 45 to obtain a desired power output, he at the same time adjusts the cams 1d and i353, the cam 1|) acting through the servo valve 8:1 and datum piston 64 to set the datum of the manifold pressure bellows 56, and the cam I acting through the rod |39 to set the datum of the aneroid 54e, and through the aneroid lil, rod iss and lever ll, to position the hydraulic metering valve at a given engine speed and altitude to obtain the necessary rise across the auxiliary stage supercharger I5. Let it be assumed that the setting of the power lever e5 calls for 30 of manifold pressure at ground level after take-off, and that the capacity of the main stage or direct engine driven supercharger is sufficient to provide the necessary charging pressure atv altitudes up to line A, Figure 6, which is assumed to be iirst critical;then up to this altitude the throttle control mechanism of Figure 2V would automaticalliT adjust the throttle to maintain the necessary charging pressure. At altitudes above line A, a boost in pressure is required trom the auxiliary stage superchargenwhich boost is'supplied up to line B, second critical, by regulating the supply of oil to the intermediate ratio hydraulic coupling 21. Preferably, the rise across the supercharger is sufcient tov slightly exceed the required manifold pressure so that correction may be obtained by taking a throttle loss, or by a slight closing of the carburetor throttle automatically brought about by the throttle control mechanism or primary manifold vpressure regulator, since this provides a reserve for sudden acceleration (note shaded area F in Figure 6). In other words, the apparatus may be set to cause the uid coupling supercharger control to drive the auxiliary stage supercharger at a speed which will produce the required manifold pressure with a slight excess and then have the faster acting and more precise throttle control correct at slight throttle loss. Above the line B and up to line C, third critical, the rise across the auxiliary stage supercharger is produced by metering oil to the high ratio coupling 21; again preferably with a reserve as indicated by the shaded area G. s v

In the position of the parts asA shown in Figure 2, it could be assumed that the pilot has set the power lever fornearly full `pov-.fer output and has climbedftoan' altitude between second (line B) and thirdv (line C) critical. Under these conditions, the throttle I6 would be approximately wide open, the valve |04 would have opened to a point where the oil flow through metering oriiices |02 had reached capacity but has been cut off by valve 3B (rendering coupling 21 inoperalever l te rotate slightly'clockwisefabout thel 11': tive), and metering 'through oricesfl E3 l'is' atape proximately half capacity and 'the 'couplingl lf-s operating at say fifty percent slip; As altitude-im-A creases, the atmospheric pressure-or yrarn `density in chamber E54 decreases, causing'the-bellows;lfili.1 to increase in length and furtheropen t'nevalie lill@ to maintain the required charging,` presiurev.

Since the oil metering'valve IEM responds-to changes in scoop or atmospheric pressure, engine R. P. M., and pilots controllever setting, and not il to changes in manifold pressure or any variable affected by supercharger speed,'the fluidlcoupling control is devoid of any tendencyto hunt. To.. explain briefly, once the desired amount of Vsupercharging is selectedby the cam.l36,as the belf lows l lil expands (assuminga gain in altitude) it maintains the charging pressure without searching for a balanced condition and the accompanying tendency to overshoot or Vhuntwhich' are present in controls where the arise across the' supercharger affects thev meteringvalve 'position which in turn affects the supercharger rise,-etc.` In such'cases, the control'may be'consi'deredfasf operating through a closed vcyclevandthe problem" of hunting issometimesan exceedingly dicult" one to solve. In the present invention, thisfac-l tor is not present, the control having-only acompensating action due to the fact that 'theaaneroid Hl@ is unaffected by the pressure it regulates, and the'prcblem of hunting istherefore eliminated; There is, of course, a closed cycle effectin the primary or throttle control, b'ut here the'engin'e" response favors this type of control; and experi; ence has demonstrated that 4an antihunt mechanism is not necessary. Again, the only tie-in loe-Y tween the carburetor throttle control and "the coupling control is at the datum settingfshaft 4! so that the two controls operate substantiallyindependently of one another while atthe same time they may be more readily scheduled to specinc types of engines, or engines having different operating characteristics.

The drive transmitting action of the iluid tcouplings is not only responsive to Aoil ll or oil flow but it is also responsive to changes in speed' on the driving side of each coupling and will 'ac cordingly vary with variation inengine speed. Ordinarily, with a variable pitch propellercoordinated with the manifold pressure` control, a` given manifold pressure corresponds1 approxi-v mately to a certain engine speed, andthese two factors may be scheduled or ycorrelated through the datum cams. But irrespectiveof the type of propeller used in the present invention, the veiect ci changes in engine speed on the couplings may be compensated for through th'eR. P. M. compensator 55E. Thus, at anyA altitude requiring' auxiliary stage supercharging, should the engine speed or R. P. M. vary from a" scheduled value G0 with respect to manifold pressure, the weights E52 will swing outwardly or inwardly/,moving rodVv i533 in a direction to increase'or decrease'the opening or closing'action-of the valveY IM andV maintain the correct rise across the supercharger.' It' will be noted that as the setting of- 'cam E35 is decreased, bellv crank |53 swings-counterclockwise and the angularity of the cam slot v161 increases,` since valve return springfi I5 willfthen-cause-the pin i4? even though the spring |42 acts through rods E39, 39 to move said pin in-a valve'closingA direction.v Thus, at lowsupercharging settings, of the cam 535 and correspondingly low engi-neL speeds, a given change in engine speed vWill 'c0m' 75 l2 pensate at approximatelyythe .=same .rateeass at: higher engine; speeds and?. supercharger;AV riser: settings.

It'will befobvious tocthosefskilledinrthe art that:

instead of regulating .aifluid"couplingorrazhye draulic valve, thezcontrolrcould-fact on algas?v` turbine; blast "gate, an electrical device; geari'se-r lection-mechanism andzthe like; and.;.althoughY only one embodiment of the invention-"hasfbeen illustrated 'and described, various changesfinfther form andY relative arrangements'fof. .the partsmayy be made to'suit requirements;

We claim:

1li In a: power control system for an aircraft engine'provided with a supercharger and arthrote Y tlc-'controlled air intake conduitterminating inf an intake manifold; al fluid .coupling for 't1-'ansetmitt-ing an ininitelyvariable; drive romlthc: engine to the supercharger, ahydraulic valve ad justable to regulate the owof hydraulic Ilui'd'totsaid vcoupling'. apower" control member suchzas: a pilots` quadrant forl` preselecting: nianiioldc pressure, andV Fmeansfoperatiyelyl `connecting'said. i member to said throttle and vsaidyalve including-,i an` aneroid responsive; to changes in ,maniolds pressure arranged to automatically-'adjust :theV` position'ofthe throttle .and another aneroiclfreev sponsive'to changes -in density of the air nov/ing` to'theengine for automatically adjustingf-isaid'., valve,v said` second named aneroid` being ,f urlare fected lay-changes in thezpressure Vregulated -by-'I the control.

2.' In a Vpower control ."system"` forxan :aircraft engine provided with'azsupercharger and a throt-lv tle controlled air intakeconduit.terminatinggin an intake manifold, a fluid .coupling riorgtransmitting an infinitely lvariable f drive@A from the: engine to the superchargen:y a". hydraulic :.valvei adjustable to regulate the .lowfofrhydraulic ud.; to. said coupling, a power "control .member such. asa pilots quadrant for Vpreselectingrmaniold'; pressure, means operatively connecting said menu ber to the throttle and also to said valve'including; an aneroid responsive to changesin; manifold pressure for automatically positioning thexthrot tie to maintain a preselected manifoldzpressura and-another aneroid responsive to changesfinthe density of the air ii'owingi to the vengineebut-y unaiectedj by changes inthe pressure tor-loe;V

0 controlled for automatically positioning:1 said;

valve, and meansactuated bymovement oflsaid: power control member for coordinating ;andcsif multaneously-setting the datum .ofthe :throttle and valve controls.

a. power control system foranlaircraft'l engine vprovided with' a supercharger and: a1 throttlecontrolled air intake conduit terminating in an intakemanifold'a iuid couplingfor'transe mitting an infinitely-variable drive "from the-.enf gineto the supercharger land a,- hydraulic ,valve adjustable to regulate the `owoffhydrauliciuidto `said coupling; in combination, manifold pressure regulator comprising. a .first aneroid; arrangedtcrespond tochanges inmanifcld pres-- sure, means operatiyely.connectingsaid.,.aneroid to. the throttle Afor. automatically positioninggthe latter to maintain pres electedmaniiold pressures up to throttle capacity, variable.datum..means. operatively connected to said aneroidy a hydraulic valve control comprising a secondaneroid ar; ranged torespond to changes in thedensity of the air flowing tothe engine butunaiectedb'y, changes in the pressure to be regulated; means operatively'connecting saidsecond an'eroi'dy to the said hydraulic valve for automatically positloningY the latter to maintain preselected manifold pressures up to supercharger capacity, variable datum means also operatively connected to said second aneroid, and a power control member such as a pilots quadrant operatively connected to both of said variable datum means in a manner such that movement of said member simultaneously adjusts the datum of both of said anerods and preselects the manifold pressure over substantially the entire manifold pressure range.

4. A power control system as claimed in claim 3 wherein said hydraulic valve is resiliently mounted and movement of said power control member positions said valve for a given altitude or air density and simultaneously sets the datum of the coacting or second named aneroid.

5. In. a power control system for an aircraft engine provided with a supercharger and an intake manifold, a device adjustable to regulate the rise across the ,supercharger, a power control member such as a pilots Quadrant, means operatively connecting said power control -member to said device including an element responsive to changes in air density and associated means adjustable by movement lof said member to maintain a selected manifold pressure at varying altitudes, andr means responsive to changes in engine speed also having an operative connection with said device for adjusting the rise across the supercharger in a manner such as to maintain the manifold pressure at the selected value irrespective of changes in engine speed.

G. In a power control system for an aircraft engine provided. with. a supercharger and an intake manifold, a device adjustable to regulate the rise across the supercharger, a power control member such as a pilots quadrant, means operatively connecting said power control member to said device including a pressure responsive device and associated means adiustable by movement of said. member to maintain a selected manifold pressure at varying altitudes, and an engine driven. speed indicator also having an operative connection with said device and arranged to maintain the manifold pressure at the selected value irrespective of changes in engine speed.

- '7. In a power control system for an aircraft engine provided with a supercharger and a throttle controlled air intake conduit terminating in an intake manifold and a device adjustable to regulate the rise across the supercharger, in combination, a primary manifold pressure regulator including variable datum means operatively connected to the throttle for automatically positioning the latter to maintain a selected manifold pressure up to substantially wide open throttle, a supercharger speed control including means coordinated with said first named variable datum means and operatively connected to said device for adjustingr the rise across the supercharger; a power control member such as a pilots quadrant for adjusting said variable datum means to maintain a selected manifold pressure at varying altitudes, and means responsive to changes in engine speed arranged to adjust said device to maintain a selected manifold pressure at a given setting of said member irrespective of changes in engine speed.

8. In a power control system for an aircraft engine provided with a supercharger and a fluid coupling for transmitting an innitely variable drive from the engine to the supercharger, a hydraulic valve for regulating the dow of hydraulic fluid to said coupling, a manifold pressure regulator operatively connected to said valve including variable datum means adjustable to preselect manifold pressure at a given altitude and engine speed, and means responsive to changes in engine speed operatively connected to said regulator and said valve and arranged in a manner such thatY variations in the drive transmitted to the supercharger through said fluid coupling resulting from changes in engine speed from a predetermined coordinated value are compensated for through automatic adjustment of said valve at a given setting of said variable datum means.

9. In a power control system for an aircraft engine provided with a supercharger and a fluid coupling for transmitting an infinitely variable drive from the engine to the supercharger, a hydraulic valve for regulating the iiow of hydraulic fluid to the coupling, a manifold pressure regulator including an aneroid and associated variable datum means-adjustable to preselect manifold pressure at a given altitude and engine speed, a power control member such as a pilots quadrant connected to said valve through said variable datum means, and an engine driven device also operatively connected to said valve and said variable datum means and arranged to compensate for variations in the drive speed transmitted to the supercharger through said fluid coupling from a predetermined coordinated value.

10. The method of regulating the rise across a supercharger driven through variable transmission means including a fluid coupling having a rotatable driven element .driven from a prime mover and a'coacting driving element drivably connected to the supercharger, which consists in metering hydraulic fluid to the coupling at a rate proportional to the speed of the prime mover.

l1. In a supercharging system for an aircraft engine wherein a supercharger is driven from the engine through variable transmission means including a fluid coupling, a valve for metering fluid to the coupling, means responsive to changes in engine speed operatively connected to said valve for positioning the latter as a function of engine speed, a device responsive to changes in air density also operatively connected to said valve, and power control means arranged to adjust said device and simultaneously modify the action of said engine speed responsive means.

l2. In a supercharging system for an aircraft engine wherein a supercharger is driven from the engine through variable transmission means including a fluid coupling, a valve for metering fluid to the coupling, means responsive to changesin engine speed for positioning the valve as a function of engine speed, another valve for regulating the flow of fluid toV said metering valve, and means for also positioning said flow regulating valve as a vfunction of engine speed.

13. In a supercharging system for an aircraft engine wherein a supercharger is driven from the engine through variable transmission means including a fluid coupling having a driving element and a driven element between whichthe slip varies in relation to oil fill, a movablevalve having one or more metering orifices for metering fluid to the coupling, engine driven means for positioning said valve as a function of engine speed, means for producing a metering differential across said oriiice or orifices proportional to the square of engine speed to flow fluid to said coupling at a rate proportional to engine speed and whereby the speed of the supercharger will vary in proportion to engine speed and a metering valve @position giving a, oertain .zp ercent slip at Vone -enginefspeed will vgive `the samepercent, slipat any engine -speed and means for: subject-y ing vsaid valve to udvpressure to automatically accelerate itsrate of movement when it is initially moved toward metering position including la port adapted to be openedr when the valve has been moved to a predetermined position.

14. In a supercharging system for an aircraft engine. having Ya supercharger provided With a rlovv speedhydraulic coupling and a high or higher speed hydraulic coupling, a valve for metering hydraulic fluid to said couplings, said valvehaving a series of metering orices or portsfor. each coupling, a'valve member which when moved to a meteringposition in a direction to increase the drive on the supercharger first uncovers the metering orices for the low speed couplinguntil minimum loW coupling slip is attained and thenuncovers the metering orices for the high .Speed coupling, and means for. automatically.producing-,en accelerated or snap-actionmovement of said 'valve member when. minimum low coupling.,

slip is attained to a position Where uid is metered to the high speed coupling, causing the llatter to quickly over-drive the low speedcoupling,v

15. Ina hydraulic metering system for 1a fluid coupling, a metering valve comprising a casing,l a valve assembly-slidably mounted in said casing and including Aa supporting memberand a valve member slidable on said supporting member, av

stop defining the limit of sliding movementof the valve member, said supporting member and valve member having spaced portions which together with the casing define a pressure chamber, means for conducting fluid under pressure to said chamberincluding a Valve port adapted to ,be opened when the supporting member has moved apref determined distancein said casing, and means resilently urging. said .valvemember toward said.

16. Inahydrauliometering system for auid coupling, a metering valve comprising a vcasing provided with an inlet port for hydraulic fluid under pressure and one or more discharge meteringports, a valve assembly slidable in said casinguand including a centralplunger havingstops position, said stepped member and plunger and.,

said valve member and stepped member being provided with pressure chambers therebetween, means for conducting uid under pressure to said. chambers includingV spaced inlet ports adaptedv to be opened successively when the valve assem bly has'been initially moved toward metering position.

17. Inl a supercharging system for an engine wherein, a supercharger isgdriven from the ,en-

gine through variable transmission means inV cluding a fluid coupling, a valve havingone .Orr more metering orifices for metering iuid tothecoupling, means for j automatically positioning said valve inY relation to engine speed, and meansformaintaining a meteringhead ordifferential across said meteringorice onorifices propor-Y tional to the square of engine speed, thus establishing a metering rate to the coupling propor. tional to engine speed directly.

FRANK C. MOCK. EDWIN G'. KELLER.

REFERENCES CITED l The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,217,364 Halford et a1. Oct. 8, 1940 2,290,884 Kollmann July 28,1942 2,297,237 Nallinger Sept. 29, 1942 2,301,653 Wells Nov. 10, 1942 2,372,326 Hewitt Mar. 27, 1945 2,380,074 Roche July 10, 194 2,400,307 Hobbs et al May 14, 1946 2,429,423 Mock Oct. 21,1947 

